** Changed in: linux (Ubuntu)
Status: In Progress => Fix Released
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https://bugs.launchpad.net/bugs/901830
Title:
A device using level triggered interrupt will not generate any
interrupts in the kdump kernel
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Oneiric:
Fix Released
Bug description:
SRU Justification
Impact
---------
In the kdump scenario mentioned below, we can have a case where the device
using level triggered interrupt will not generate any interrupts in the
kdump kernel.
1. IO-APIC sends a level triggered interrupt to the CPU's local APIC
2. Kernel crashed before the CPU services this interrupt, leaving the
remoteIRR
in the IO-APIC set
3. kdump kernel boot sequence does clear_IO_APIC() as part of IO-APIC
initialization. But this fails to reset remoteIRR bit of the IO-APIC RTE
as the remoteIRR bit is read-only.
4. Device using that level triggered entry can't generate any more interrupts
because of the remoteIRR bit.
In clear_IO_APIC_pin(), check if the remoteIRR bit is set and if so
do an explicit attempt to clear it (by doing EOI write on modern io-apic's
and changing trigger mode to edge/level on older io-apic's).
Fix
----
upstream commit 1e75b31d638d5242ca8e9771dfdcbd28a5f041df
Testcase
------------
TBD
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